Electric motor control equipment



Se t. 27, 1938. w. 'r. GRAY ELECTRIC MOTOR CONTROL EQUIPMENT Filed Jan.25, 1937 5 Sheets-Sheet l Inventor:

WiIIiamTGPa by 74/ Hi Attorney;

Se t. 27, 1938. w. 'r. GRAY 2,131,538

' ELECTRIC Moron CONTROL EQUIPMENT Filed Jan. 25, 1937 5 Shets-Sheet 2Inventor": William T Gray,

by C His Attorney.

Sept. 27, 1938.

lmau mm- W. T. GRAY ELECTRIC MOTOR CONTROL EQUIPMENT Filed Jan. 25, 19375 Sheets-Sheet 3 Fdl LS2 J f5 1 F J 3 a I; .l T .1 A, W

A 1 2 w J Inventor:

H IS tor-hey.

Sept. 27, 1938. Q I w 1' GRAY 7 2,131,588

ELECTRIC MOTOR CONTROL EQUIPMENT W z@ W W X@ W 5W mkw- W W m w w 75% m Wk I Inventor:

William TGray,

His torney.

I Sept. 27, 1938. w GRAY 2,131,588

ELECTRIC MOTOR CONTROL EQUI'PMENT Filed Jan. 25, 1937 5 Sheets-Sheet 5Invent or: 'Wi I 1 Earn T. GTay.

HIS Attorney.

Patented Sept. 27 1938 UNITED STATES ELECTRIC MOTOR CQNTROL EQUIPMENTWilliam Train Gray, Altrincham, England, assignor to General ElectricCompany, a corporation of New York Application January 25, 1937, SerialNo. 122,286

In Great Britain February 3, 1936 I 10 Claims.

This invention relates to control equipments for electric motors havingseries field windings, of the kind in whichduring accelerationresistance is progressively cut out of the motor circuit 5 andthereafter the field windings are shunted in order to weaken the motorfields. Theinvention has for its object to provide a particularlyadvantageous control equipment of this kind in which a large number ofaccelerating notches is obtainable, the accelerating resistance beingfinely variable, and also the degree to which the field is weakenedbeing finely variable. The invention is particularly, but notexclusively applicable to control systems for electric traction motors.

According to the invention a control equipment of the kind specifiedcomprises a resistance divided into a number of sections adapted to beinserted in the armature circuit and switching means which, in responseto actuation or movement of a control element for causing accelerationof the motor, initially places said resistance in series withthearmature and series field winding of the motor, first in a single pathconnection and subsequently in a series of multiple path connections.The switching means is further arranged so that in order to obtainfurther accel- 'eration by weakening the field of the motor, saidresistance or part thereof is connected in parallel with the seriesfield winding or a part thereof and then reduced progressively by asequence partly or wholly in accordance with the previous sequence bywhich the resistance is removed from the armature circuit.

The switching means may be of any desired form and may be controlled byany desired type of controller. As shown, the switching means comprisesa drum controller operated automatically or. as shown, the switchingmeans may comprise electromagnetically. actuated contactors thecontrolling circuits of which are operated from a sequence switch.

The invention further contemplates the use of a resistor comprising anumber of series connected sections with lateral tapping connectionspassing via a switch in each to a bus wire, and a second series oflateral tappings intercalated with the first series. also passing viaindividual switches to a second bus wire, which is broken by furtherswitches, between successive tappings or between some of the latter, thearrangement being such thatby a graduated sequence 'of tapstepping andof interconnecting of tappings the effective value of resistance imposedupon the circuit by the resistor may be varied from that corre- 55sponding to a single path through the series of resistor elements, downto that involved by a multiple connection of the load circuit to aplurality of tappings together with a similar multiple connection of thepower supply line to a plurality of other tappings intercalated with thefirst. The said switches may for example be separate switch devices suchas contactors or may be constituted by suitably arranged contacts of adrum type or like controller, the two bus wires in the latter case beingconveniently constituted byqconnections between appropriate contactsegments on the controller drum or the like.

Where a drum typeswitch is employed the contact fingers of said switchare divided into two groups of adjacent fingers associated respectivelywith the two sets of alternate tappings of the resistance, and theconnection between one set of tappings and-the associated group offingers cross the connections between the other set of tappings and theassociated group of fingers. 20 By this means the contact segments ofthe drum switch are required only to be connected with adjacentsegments, as will hereinafter appear, and the otherwise necessaryextensive interlacing of connections in the drum between the severalcontact segments is rendered unnecessary.

The equipments according to the invention may include any desired numberof motors, and as shown two motors are employed and the equipment isarranged for series-parallel operation of the motors.

. According to a further feature of the invention a control equipmentfor providing series-parallel operation of two or more electric motorswithweak field operation for further acceleration comprises for each ofthe motors a'resistance arranged to be usedin many combinations of partsthereof affording single and multiple current paths and serving both asan accelerating resistor and for field shunting, as set forth above, andthe switching means comprises a master controller and a servo-operateddrum type switch by which the connections of each of the resistors forsaid combinations are effected, with further switching means andinterlocking arrangements whereby circuits carrying the main current arebroken by said further switching means before being opened on the drumswitch. Said further switching means may be of any suitable formadaptedto break current carrying circuits, for example electromagneticcontactor switches.

In carrying out this feature of the invention, the transition betweenthe series and parallel operating conditions of the'motors is preferablyeffected by means of the well known bridge may be so arranged that nofurther switching means capable of breaking the main current arenecessary, namely other than those normally pro vided for effecting thetransition.

According to a further feature oi the invention the transition isinitiated by interlock contacts carried. on the drum switch. Thus, wherea bridge transition is employed, said interlock contacts are arranged toenergize the controlling or operating circuit of the well known Jswitchare reinserted in circuit with theirrespective motors and the twofurther line switches provided in bridge transition equipments are thenclosed through suitable interlock contacts. Further movement of the drumswitch causes progressive of field windings Fdl transition system inwhich case-the equipment Referring first to Fig.1, the equipment isillustratedas including two traction motors which are operatedpermanently in series with one another. The armatures of the two motorsare indicated respectively at MI and M2 with respective series fieldwindings FdI and Fdi. The two sup-. ply conductors for the equipment areindicated. respectively at TI and T2 being connected with the equipmentthrough respective line switches LSI and LS2. The acceleratingresistance comprises twelve sections H to H2 inclusive, the resistancebeing provided with end connections A and M and intermediate tappings Bto L inelusive.

A contactor RI is provided for connecting the 1 end A of the resistancewith the line switch LSI whilst the other end M .of the resistance isadapted to be connected with one end of the pair and Fd! through acontactor F2. be connected directly with the line switch LSI by. way ofa contactor FI under certain conditions as will hereinafter appear. Acontactor F3 is provided for connecting the end M of the resistancedirectly with the motor armatures MI and M2 5 under certain conditions,as will also hereinafter appear. Further contactors for governing theremoval of the resistances from the circuit are The field windings arealso adapted to m removal of the resistors from the paralleled motorcircuits. With the arrangements according to the invention employing adrum switch the arrangement of said switch is preferably such that inpassing to the first weak field notch, namely in removing the resistorsfrom the armature circuits and reconnecting said resistors across theseries field windings no current carrying circuits require to be broken,but the alternative circuits to which the currents-are transferred areestablished prior to the opening of the necessary current paths at thedrum switch.

In order that the invention may be clearly understood reference will nowbe made by way of example to the accompanying drawings in whicho Figure1 is an electrical diagram illustrating one embodiment of the providedas indicated at R2 to RII inclusive. The contactors R4, R1, RI 0, RI3,and RIG are respectively arranged to connect the tapping. points D, F,H, J and L of the resistance with a bus wire BI which is connected withthe line switchLSI. The contactors R2, R3, R6, R9, RI2 and RI5 are 85 Iand K respectively with a second bus wire B2 in which the contactors R5,R8, RI I, R and R" are interposed in series with one another, which buswire B2 is connected between the ends A and M 01 the resistance. Thecontactors may be either electromagnetically or electro'pneumaticallyactuated and controlled by a suitable control circuit (-not' shown)conveniently comprising a sequence switch arranged to provide theswitching sequence indicated in Fig. 2, the sequence arrangedto connectthe tapping points B, C, E, G, 35 I "iii contactor type switches,

Fig. 2 is a sequence chart of the kind well understood by those skilledin theart, showing the.

operation of the contactors of Fig. 1 in accelerating the 'motorequipment, and illustrating the principle of resistance notchingpreferably employed in carrying out the invention.

Fig. 3'comprises a series of circuit diagrams Fig, 4 is an electricaldiagram showing the arrangement of the main circuits in a preferredembodiment of the invention for traction equipment, employing a drumtype switch and providing series parallel operation of a pair of motorswith field weakening operation under parallel conditions, v

Fig. 5 is a simplified diagram showing the main circuit arrangement ofFigure 4,

Figs. 6, '7, and 8 are diagrams similar in nature to Fig. 3 and showingthe sequence of switching operations performed on the various positionsof the drum switch of Fig. 4 during series, parallel and weak fieldconditions respectively, and V,

Fig. 9 is a control schematic diagram showing the control circuits forgoverning the operation of the equipment shown in Fig. 4.

invention employing chart of Fig. 2 the contactors which are closed onthe various notches or stages p0 of the accelerating operation areindicated by circles, the notches being represented in the tophorizontal column of the chart and the switches in the left-handvertical column. In operation, the line switches LSI and LS2 are closedon all notches. The contactor F2 is closed on all notches i to 65inclusive and the maximum full field notch FF but is opened on the subsequent notches providing weak field operation as will hereinafter appear.contactor RI is closed in addition to the line switches LSI and LS2 andthe contactor F2 with the result that power is MI and M2 through thewhole resistance A to M,

1 as shown in Fig. 3 under notch I". .On the next 15 replaced by a drumswitch or On the first notch the to applied to the motors contactors RHand RI are closed to remove the 1 three notches the contactors R2, R3and R4 are closed in turn whereby the sections TI, TI, and r3 areprogressively removed from the motor circuit. On the fifth notchcontactors R5 and R6 are closed to remove the section 11. The contactorR1 is then closed to remove the resistance section r5, whilst on thenext notch the contactors R8 and R9 are closed to remove the resist ancesection 16. On the eighth notch the resistance contactor RIB is closedand the resistance section 'r'I removed; on the ninth notch thecontactors RH and RIZ are closed to remove the resistance section 18,and on the tenth notch the contactor RI 3 is closed whereby theresistance section T9 is removed. On the eleventh notch resistancesection 1H) and on' the twelfth notch contactor RIG isclosed whereby themotor armatures and field windings are connected across the supplyconductors TI and T2 through resistance section rI2 alone, as shown atnotch I2 in Fig. 3. The contactors RI to RI5 are all opened on thetwelfth notch. On the thirteenth notch, indicated at notch I3" Fig. 3,the contactors R5, R8, RI I, RH and RH are all closed whereby the buswire B2 is connected across the ends A and M of the resistance, and theresistance sections TI to .rII inclusive thereby connected in parallelwith the resistance section rI2 to efiect a further reduction of theresistance, these conditions being indicated at I3 inFig. 3. Thecontactors R2,

R3, R6, R9, RI2 and RI5 are then closed in turn to remove the resistancesections H to H0 inclusive progressively in six further steps whereby onthe .nineteenth notch the resistance sections rII and rIZ are left incircuit in parallelwith one another, as shown at notch I9" in Fig. 3. Onthe twentieth notch the various resistance contactors R2, R3, which wereclosed on the previous notch are all opened except contactors RI5, RIBand RI! and the contactor RI is again closed to reconnect the end A .ofthe resistance with the line switch LSI whereby the resistance sectionsTI to 110 inclusive are connected in parallel with the sections rII andH2, as shown at "notch 20 in Fig. 3. Thereafter by a switching sequencesimilar to that employed between the first to the tenth notch theresistance sections H to r9 are progressively removed from the circuitso that on the twenty-ninth notch the three sections rIO, rII, rI2remain in parallel with one another. The contactors RI to R4 inclusive.R6, R1, R9, RIII and RIZ are then opened and the contactor RH closed toconnect the resistance sections TI to 1-9 inclusive in parallel with thesections rIIi, HI and rll, as indicated at "notch 30" in Fig. 3.

From aninspection of the sequence chart of Fig. 2 and the diagrams undernotches 38,, 49, 55, 59 and 63" of Fig. 3, it willbe seen that sequencessimilar to those above described are repeated in turn on. the remaining.sections of resistance so that on the thirtysix'th, forty-fourth,forty-ninth, fifty-fifth, fifty-ninth and sixtythird notches aprogressively increasing number of the resistance sections are connectedin parallel with one another with the othersections in series withone.another, io'rming a further parallel circuit, which series-connectedresistances are progressively removed from circuit during theintermediate notches to leave the last section only in parallel.Finally. on the sixty-fifth notch, the resistance sections r3 to 1|!inclusive are all connected in parallel with one another, which in theequipment illustrated provides the lowest value of the resistance. Onthe next notch FF providing the maximum speed full field operation thecontactor RI is closed in addition to the other contactors whereby theresistance is completely short-circuited through said contactor RIandthe bus wire B2, as indicated under notch FF in Fig. 3.

In proceeding to weak field operation the contactor F2 is opened andcontactor Fl closed whereby the main motor circuit proceeds from theline switch LSI through contactor FI field windings Fill and FM andarmatures MI and M2 to the line switch 152, the contactors R2 to RI!being all opened. Contactors F3 and RI are however closed, with theresult that the whole of the resistance A--M is connected in shuntacross the field windings to provide the first weak field notch, that isthe minimum value of field weakening. These connections are indicateddiagrammatically at notch WF" in Fig. 3.

The resistance sections rI to 1'I2, inclusive, are then againprogressively reduced in accordance with the sequence above describedfor the full field operation, the first such resistance reducing notchonly being shown in Fig. 2. It will be understood however that thesequence is continued in accordance with the whole or a part of thesequence of the first sixty-five notches to provide progressivelyincreased field diverting operation.

It will be understood that the resistances rI to H2, inclusive, aregraded in order to obtain a desired variation of the resistance duringthe accelerating period. Usually it will be required that a relativelyhigh initial resistance is available to deal with stand-stillconditions, which one-hundredth, or even very much less. It will beappreciated that the design of the various sections of resistances, inorder to obtain any given requirements, will proceed according tomethods well known to those skilled in the art.

It will be observed that with the arrangementaccording to the inventiona very large number of values of the resistance is obtainable with arelatively small number of resistance sections and switches. Fig. 1,sixty-five different values of resistance are obtained by the employmentof only twelve resistance sections and seventeen switches. thermore,these resistance sections and switches are employed both for theprogressive removal of series resistance from the armature circuit orcircuits and for the progressive field weakening.

It will be appreciated that it is not essential to-employ all thenotches provided by the sequence above described and that some 01' thesenotches may be omitted in carrying out the invention. For example, somesteps may be omitted during iull field'operation whilst the same and/orother steps may be omitted during the weak field operation, andsimilarly, the same and/or. other steps may be omitted in the case of anequipment having a plurality of motors arranged for series paralleloperation, when the motors are operating in parallelwith one another. Ingeneral, when the resistances are connected in series with the motorarmature or armatures the higher values of resistance will usually bemost effective whereas in the field shunting connections the lower rangeof valueswill usually be useful.

Fur-- For example with the equipment of dli -motor MI is having sectionsRBI to RR! inclusive whilst the a pped resistance .ment includes twocontactor switches spectively with associated series field windings Filland F112 and are adapted to be connected across the supply conductors TIand T2 by means oi line switches LSI, L82, L83 and LS4. The providedwith a tapped resistance motor M2 is provided with having sections RI toRi inclusive, The equip- JR and J for providing transition of the motorsfrom series to parallel operating conditions inaccordance-with thewell-known'bridge transition system as will be apparent fromthesimplifled diagram of Fig. 5.

Reverser switches IOI and I 02 for the motors MI and M2 and may becombined into a single switch which .is of the kind adapted to be thrownto one or other oi its operative positions by electro-magneticallyactuated or controlled means.

The tapping points of the resistance RBI to RR! are connected withcontact fingers I03- IOB inclusive of a drum switch indicated in theconventional manner. prises two mechanically are provided convenientlycoupled portions I08 and H0 associated with the motors MI and M2respectively and having operative positions I45 inclusive indicated bythe dotted lines in Fig. 4. The portion III! of the drum switch includescontact fingers III-ll inclusive which are connected with the tappingpoints of the resistor RI to R5. The drum switch further includescontact fingers II! and H8 co-operating'with the segments or the portionI09 and connected together by way of a conductor to and through thereverser I III ings Fdl remote tact finger H9 is with the side of thefield windi'rom-the armature Ml. A conconnected between the switches 153and JR, an .a further contact finger I is connected with the armature MIby way of a resistance HRS, the purpose of which will hereinafterappear. Similarly the portion H0 of the drum switch includes contactfingers PM and I22 connected together over a conductor I220. and throughthe reverser I102 with the side of the field windings Fd2 remote fromthe armature M2. A contact finger M3 is connected between the switchesLSZ and JR, whilst a further contact finger IN is connected through aresistance R6, similar in function to resistance RRIB, with the armatureM2. 7

It will be observed that the connections between these tapping pointsand controller fingers are divided into two groups, one group crossingthe other, so that one set of alternate tappings, namely a and c, areconnected with the first group of adjacent contact fingers Illli, IN andIM, lid and the other set of alternate tappings, namely b and d with asecond group of fingers IM, Hi3 and Ill, lit. By this means theotherwise necessary extensive crossing of conductors between segments ofthe drum switches is avoided. The segments of the drum may be built upin simple units, each unit comprising all segments which are connectedtogether and the units being fitted together from opposite ends of thedrum. The units of segments may conveniently each be constituted byfasingle simple casting to which contact strips proper may be secured.

The drum switch is provided with two sets of auxiliary or interlockcontacts I25 and I26 forming part of the control circuits for theequipment and the function and operation or which will A second .pistonis said piston to the initial po This drum switch comforward and reversewires hereinafter appear in the description of Fig. 9,

in which these interlock contacts are shown in the usual schematicmanner. The coils of overload relays are connected at OM and CL! coil ofa limit switch for governing the accelerating operation of the equipmentis indicated at I21.

The drum switch is actuated by aservo motor device (notshown) controlledby the contacts of the limit switch so as to allow movement of thedrumswitch when the armature current of the motors is below apredetermined value. In the example of the invention being describedthis servo motor device is arranged as set forth in the specification oiBritish-Letters Patent No..

451,514. This servo motor device comprises a piston subjected to aliquid pressure obtained by the,app1ication of air valve which governsthe flow of liquid to the piston whilst a valve is provided forcontrolling the application of said air pressuresaid valves beingprovided with operating coils connected as hereinafter describedwithreference to Fig. 9. provided for returning the drum and the first Isition upon application of air pressure to the second piston. Thispiston is governed by a valve herein termed the ofl" valve whichnormally connects the cylinder in which said piston operates with theair pressure; source but when the operating coil for said valve isenergized said cylinder is vented to atmosphere. A relief valve operatedby an electromagnetic coil is provided for allowing relatively quickreturn movement of the plunger as described in the earlier specificationaforesaid. The operating/coils of the two last mentioned valves areconnected in the control circuit as will hereinafter be described.

Referring now to Fig. 9, the control circuit is energized fromconductors I28 and I29. The circults are governed by a master controllerindicated generally at MC having theusual deadmans-handle contactsindicated at I30, an accelerating drum I3I having an off position 0 andoperative positions I-5 inclusive and a reverser drum I32.

The conductor I28 is connected with the equipment through the usualcontrol governor I33 from whence the circuit branches on the one hand-tothe trip and reset push-button switches lit and n35 respectively, and onthe other hand over conductor I3t to, the 'dead-mans-handle contactsI30; From the contacts I30 a circuit proceeds to a contact finger 8% onthe reverser drum I32 whilst the contacts ltd are also con- 7 nectedwith ya contact finger it! oil-operating with the contact segments oithe drum Itl. The drum I it is arranged alternatively to energize I38and I39 from the contact finger I36 accordingly as the drum is actuatedto the forward or reverse position. The accelerating drum ltico-operates with five further contact fingers connectedrespectively withconductors ltd-Wt respectively. The drumv lltl is arranged to energizethese conductors successively in movement from. the oil to the fifthposition. The trip and reset switches tit and we are arrangm to energizeconductors Hi5 and Mt respectively, the conductor M6 including contactsit? closed by the drum I3I only in the ofl position of the latter. Afurther conductor M8 is connected with the sameside of the contr-oicircuit supply source as is the conductor I28.

respectively, whilst the operating.

pressure tothe liquid. The movement of the piston is controlled by aspectively with the operating coils I54 and I55 for actuating thereverser to the forward and reverse positions respectively. The reversercarries interlock contacts I56 arranged when the reverser has beenthrown to the. position corresponding to that one of the wires I38 andI39 which is energized, to cause energization of a conductor I51 fromthe energized-conductor I38 or I39. The conductor I51 is connected withtheoperating or control coils OCLSI and OCLS4 of the line switches LSIand LS4, the circuit proceeding through contacts I58 of a no-voltnocurrent relay and an interlock contact I59 carrled by the drum switch(Fig. 1%) and closed only when said switch is in the ofi position. Thelast mentioned contacts are shunted by interlock contacts I66 carried bythe line switch LSI and closed only when said switch is open. Thecircuit of the operating coils OCLSI, OCLS4 is completed to theconductor I29 by way of over-load relay contacts I6I. The conductor I40proceeds by way of conductor I40a, interlock contacts I62 carried by theline switch LS3 and closed only when the latter is in the openposition,and interlock contacts I63 carried by the switch J and opened when thelatter is in the closed position, to the operating coil OCJR of theswitch JR.

The conductor I40 also proceeds by way of a branch I40b throughinterlock contacts I64 carrled by the line switch LS4 and closed whenthe latter is in the closed position to a contact finger I65co-operating with interlock contact segments I25 of the drum switch. Theinterlock contacts I64 are shunted by contacts I66 carried by a trippingelement by which the overload relays are operated to trip the lineswitches upon energlzatlon oi the conductor I45 from the trip pushbuttonI34, the conductor I45 including an operating coil I61 for actuating thesaid tripping element when said coil is energized.

A conductor I40c branched from the conductor I40a is connected withoperating coils I68 and I69 of the ed and release valves of the servomotor. Thus, when the coil I68 -is energized the return cylinder of theservo motor is vented to atmosphere whilst the coil I69 when energizedcloses the relief valve in the fiuid part of the servo motor. Theoperating 0011.0! the valve by which air pressure is appliedto theliquid system of the servo motor is indicated at I10, this valve beinghereinafter termed the on valve and being opened when the coil I10 isenergized. The energization of this coil is eifected'from. a contactfinger I1I of the interlock contacts I 25 of the drum switch. Theseinterlock contacts are arranged so that the finger "I is energizedeither from the finger I85 or when the drum occupies its first positionfrom a contact finger I12 connected with the conductor I48.

The interlock contacts I25 include further segments which in the seriesand parallel ranges of movement of the drum switch connect contactfingers I13 and I14 respectively with-the finger I85 and thus with theconductor I401). The

finger I18 is connected with the operating coil OCJ of the switch J byway of interlock contacts I15 carried by the line switch LS3 and closed'only when'the latter is in the open position. The contact finger I14 isconnected with the operating coils OCLS3 and OCLSZ of the line switchesLS3 and LS2, the circuit including interlock contact I16 carried by theswitch JR and closed only when the latter'is in the open position andcontacts I11 of the no-volt no-current relay. The coil of the feed valveof the servo motor device is indicated at I18 having connected incircuit therewith the contacts I19 of the current limit switch whichcontacts are opened when the armature current of the motors rises abovea predetermined value. The circuit of the coil I18 is adapted to beenergized by way of the interlock contacts I26 from the conductors I toI44 inclusive in the manner hereinafter described. The conductor MI isconnected with a contact finger I90 connected-by the segments I26 withcontact fingers I8I and I82 when the drum switch occupies a positionwithin the range of series operating conditions. The finger I8I isengaged by its co-operating contact segment throughout the completerange of movement of the drum switch, whilst the finger I82 is engagedonly in the series positions. The circuit of the feed coil I18 isconnected with the finger I8I by means of interlock contact I83 carriedby the switch JR and closed only when the latter is in the openposition.

The conductors I42, I43 and I44 are each connected with the operatingcoils of respective relays I84, I85 and I86 which, when their coils areenergized, close their contacts to connect the conductors I42, I43 andI44 with contacti'lngers I81, I88 and I89 respectively of the interlockcontacts I26. The provisionv and arrangement of said relays I84, I85 andI86 forms the subject matter of British application No. 15,536/36 and itis to be understood that no claim is herein made to such arrangements.The contact segments co-operating withthe fingers I81. I88 and I89 arearranged so that the finger I81 is connected with the finger I8I whenthe drumswitch occupies a position providing parallel operatingconditions of the equipment. The finger I88 is connected with finger I8Iwhen the drum occupies the firstportion of its range of movementproviding weak field operation and the finger I89 is connected withfinger I8I when the 'drum switch occupies a position within the secondportion of its range of movement providing weak field operation, that isits final range of movement.

The interlock contacts I28 01' the drum switch comprise further fingersI90, I9I and I92 and segments which connect the fingers I90 and I9Itogether when the drum switch reaches the parallel position and thecontact fingers I9I and I92 together when the drum switch reaches thefinal position. Contact finger I90 is connected with the conductor I93to which the finger I92 is connected by way of interlock contacts I94carried by the line switch LS4 and closed only when said line switch isclosed. A test plug or the like is provided at I95 whereby theconductors I98 and I96 to which the contact finger I9I isconnected, maybe short-circulted under certain circumstances, referred to hereinafter,the circuit oi. the conductors I93 and I96 through the interlockcontacts I26 of the drum switch being. employed for test operation, tobe described hereinafter."

The conductor I46, which is adapted to be envNi m circuit proceedsthrough the five resistance.sec-' ergized by operation oi the resetpush-button I35, is connected with the resetting coil its of theover-load relay, the circuit including interlock contacts I98 formingpart of the contacts I25 and closed only when the drum switch occupiesthe "oiP position.

In the operation or the above described equipment, assuming the reverserdrum I32 (Fig. 9) to be actuated to an operative position, thecorresponding forward or reverse wire I38 or I 39 will be energized,thereby to energize the appropriate coil WI or IE5 to throw the revcrserIN and W2 (Fig. 4) in the required direction. The conductor I51 isthereby energized and through the nocurrent relay contacts i 58 and theinterlock contacts I59 of the drum switch, which is in its firstposition, referred to as the initial or "off" position, said conductorcauses energization of the coils 'OCLSI and OCLS4, whereby the lineswitch LSII and LS4 (Figs. 4 and 5) are closed and the equipment thusconnected with the supply condoctors; TI and T2. Assuming now that theaccelerating drum I3i of the master controller is actuated to anoperative position the conductor I40 becomes energized and its branch I40:: energizes 'thecoil OCJR to close the JR switch, the interlockcontacts I62 and I08 being closed at this time since the line switch LS3and the switch J are open. Consequently in this position of the mastercontroller the main power circuit proceeds from supply conductor TIthrough the coil v OLI of the overload relay associated with the motorMI, through the line switch LSI, motor armature Mi, reverser IN andseries field winding FdL-to the contact finger IiB'ot the drum switch.In the initial or "ad" position of the drum switch which is occupied bythe latter at this time the finger H8 is connected with the finger I bythe segments of the drum and the tions RRB toRRi inclusive to thecontact finger I which is engaged by a contact segment connected with pthe linger lit. From the finger lit the circuit proceeds through the JRswitch to the contact finger its oi the portion iill of the drum switch,through the segments of the latter to the finger H4, and thence by wayof the resistance sections R2, Rt, M and R5 to the 0Oi1-.

tact finger I it which is connected through the drum segments with thecontact finger I22. The circuit continues through the reverser Hi2 andseries field winding F1122 to the armature M2 and thence by way of lineswitch LSE, series coil I21 oi the limit switch and the coil 0L2of theoverload relay associated with the motor-1M2 to the supply conductor T2.The two motors are thus connected directly in series across the supplyconductors with nine sections or the two re- V in readiness for movementsistances inseries therewith the arrangements of said resistance beingindicated at notch P in ,Fig'. 6. The equipment is thus connected forminimum. speed operation and unless the master .controller is-actuatedto a .further'position no removal of the accelerating resistances takesplace. 7 u In the flrst'or oil position of the drum switch the-interlockcontacts i2! connect the contact fingers H2 and I ll together toenergize the coil 1 I from the conductor I48. Air pressure is thusapplied to the liquid system of the serv'o'motor or the drum switch byenergization of the coils I60 and I80 01' the "oil" and relief valvesand the, coil I18 of the feed valve. By this means the time otherwisecc-es sary for raising the air in the system to the oper i its secondposition degrees included in the centre of Fig. 4

as above described. Assuming now that the master controller is operatedto any one of its operative positions 2-5 inclusive conductor MI isenergized from the drum I3I, whereby the contact finger I82 oi theinterlock contacts I26 of the drum switch is energized from the finger Iso. through the associated segments. The feed coil are of the servodevice for the drum switch thus becomes energized under control of thelimit switch I10 and movement of the drum switch to is thus permittedthereby to maintain thearmature current of the motors at the valuedetermined by the setting of said limit switch. on the second andsubsequent positions of the drum switch the finger ill of the interlockcontacts I is disconnected from the finger I12 and connected with fingerI 65 whereby the energization of the coil'l'l0 is transferred from theconductor I48 to the conductor IIIIIb so that subsequent de-energizationof conductor Oh will result in return of the drum switch to the firstposition as will hereinafter be described. Under control of the limitswitch contacts I18 the switch will now move forwarduntil, assuming theaccelerating drum I3'I occupies the second Figs. 4 and 9, which is thesixteenth notch or the sequence as indicated in Fig. 4, and provides thefull series operation. Under these conditions the circuit of the feed,coil Ilt becomes broken I and further movement of the drum switch isprevented.

The arrangement i the resistance sections Ri-Rt and RR! to l utilized onthe series notches I--it or the equipment are shown in Fig. 6 and itwill be seen that the removal of renstances proceeds generally inaccordance with the principle described with reference to Figs. 1, 2 and3; but a considerable number oi the possible combinations oi theresistance sections are omitted. Therelatively great number oi notchesindicated in Fig. 2 are not the equipment being described. Furthermorethe series operation comprises only about one-third of the completerange of notches. It will be noted that in certain cases the angulardistance between adjacent notches as indicated by the scale of has beenincreased-for example, between the twelfth and thirteenth notches. Bythis means it is impossible for the power connections to proceed fromrequired in the twelfth to the thirteenth combination withing only theresistances RBI to RR! connected all in parallel with one anotherasshown' at notch II, Fig. 6. On the sixteenth notch the conductor I40b(Fig. 9) which is energized by the conductor I40 is connected throughthe fingers I05 and I18 01 the interlock contacts I25 with the coil OCJof the switch J the line switch LS2 being.

gize the coil of relay I34 which closes its conswitch may thus be brokenwithout any arcing occurring at the latter.,

Assuming that the accelerating drum I3I (Fig. 9) now occupies the thirdor subsequent position the conductor I42 is energized to enertacts tocause energization of finger I31 of the interlock contacts I23, saidfinger I31 thus becomes connected (in the full series position) with thefinger I3I and since the JR switch has been opened uponde-energizationof its coil OCJR due to opening of the interlock contacts I33 resultingfrom closure of the switch J the finger I3I is connected through .theinterlock contacts I33 with the feed coil I13. The interlock, contactsI33 are made sufilciently long as indicated to ensure that the switch JRshall not be opened until the switch J has closed. Movement of the drumswitch may now proceed under control of the limit switch contacts I19.This further move ment causes, on the seventeenth notch or the.

drum switch, the finger I14 to be energized by way or finger I35 andconductor I40b. Energize.- tion of finger I14 results in energization ofcoils OCLS3 and OCLS2, since the'interlock contacts I13 carried bytheswitch JR are closed as the latter is now open, and the line switchesLS3 and LS4 are thereby closed. In its movement from the sixteenth tothe seventeenth notch the drum switch has rearranged the connections ofthe accelerating resistances so that four sections of each of the-latterare now included in circuit with each motor respectively. The closure ofline switch LS3 causes opening or the interlock contacts I15 whereby thecircuit oi the coil OC'J is broken and the switch J thereby opened andthe transition completed.

The circuit for the motor MI thus now pro ceeds (Fig. 4) from supplyconductor TI through line switch LSI, armature MI, reverser IIII andfield winding Fdl to contact finger II3, through drum switch segmentsand resistance sections R35, RR4, RR3 and RR2 to finger I03. From thisfinger the circuit proceeds through the drum switch segments to thefinger II3, line switch LS3 and to the supply conductor T2.

The circuit for the motor M2 proceeds from the supply conductor TIthrough line switch LS2, contact finger I23, drum switch segments,finger II4, resistances sections R2, R3, R4, R3, to finger II3. Thedrumsegments connect finger II3 with finger- I22 from. whence the circuitcontinues through reverser I02 and field winding Fd2 to the armature M2;line switch LS4 and supply conductor T2. These circuit conditionss'ition. By this means a large angular movement isobtained in which the"drum may be stopped in the event of switch J failing to close throughmischance without sacrificing the. de-

sired creepage distance between such segments as those engaging withfinger I03 which on the sixteenth and seventeenth notches areconnectedto segments of opposite polarity. As will be seen from an inspection ofthe segments H0 and I03 in Fig. 4 theseveral contactfingers are arrangedto be disengaged by the associated segments one at a time so that thetorque required to turn the drum in the reverse direction is notexcessive as would be the case if it were necessary to raise aconsiderable number of fingers simultaneously.

Under control of the limit switch contacts I19 the movement of the drumswitch proceeds forward/ from the seventeenth notch to the thirtysecondnotch providing full parallel operation of the'equipment. The sequenceby which theresistanc'es are removed from the motor circuit will beapparent from inspection of .Fig. 4, and are shown in detail in Fig. 7.It will be seen that the sequence again follows the principle employedin the arrangement-of Figs. 1, 2 and 3, the notches employed accordingto Figs. 4 and '7 being, however, those most useful for the accelerationof the equipment during the parallel operating conditions of the twomotors and the resistance being notched out of the two motor mate notchof the parallel operation.

On the thirty-second or full parallel notch the contact fingers H1 andI2I become again'connected directlyby the drum segments with the fingersH9 and I23 respectively and thereafter, namely between the thirty-secondand thirtythird notches, the various contact fingers I03 to H8inclusive, III to H3 inclusive and I to 2 are disengaged by the segmentsin preparation for the-reconnection of the resistance sections acrossthe field windings.

Thus on the thirty-second notch each of the motors is connected directlyacross the supply conductors TI and T2 by way of a circuit which for themotor MI proceeds throughline switch LS I, motor armature MI, reverserI0 I, field winding Fdl. conductor II3a, finger II1, drum segments,finger II9, line switch LS3, whilst the circuit for the motor M2proceeds through line switch LS2, contact finger 123, drum switchsegments, finger I 2], conductor I 22a, reverser I02, field winding Fd2;armature M2, and line switch LS4. If the master controller occupies itsthird position corresponding to full parallel operation, no furthermovement of the drum switch can occur since. on this notch the fingerI31 is disengaged by its associated contact segments of the interlockcontacts I23 and the circuit of the feed coil I13 is thus broken at saidinterlock contacts since the conductors I43 and I44 are not energizedunless the master controller occupies the fourth or fifth positions.

Assuming now that the controller occupies the fourth position, theconductor I43 becomes energzed whereby the relay I35 is actuated toclose its contacts and energizes the contact finger I33 whereby theenergization of the circuit of the feed coil I13 is continued andfurther movement of the drum switch is possible under control of thelimit switch contacts I13. The drum switch is thus actuated to itsthirty-third position in which the finger I03 becomes connected with thefinger I20, the connection or finger I03 with winding is made by finger.H8 having been terminated immediately after the full parallel position.The upper end of the resistances RR5 to RRI inclusive are thus connectedbetween the armatureMI of the associated field winding FdI. The fingerI04 is connected with the finger H9 and also with the finger H1 and thusto the other end of the field winding. Consequently the resistancesections RR5, RR and RR3 are connected in series across the fieldwinding Fdi to provide the first weak field operation.

Similarly in the thirty-third position the contact finger I24 isconnected with the contact finger II6, whereby the lower end of theresistances RI to R5 inclusive is connected between the armature M2 ofthe field winding F112. The finger I I2 is connected with the fingersI23 and IQI whereby the resistance sections R3, R and R are connectedacross the field winding Fd2; the arrangement of the resistance sectionsunder these conditions is shown at 33 in Fig. 8.

It will be noted that the connection of the accelerating resistancesacross the respective field way of the resistances RR6 and R6respectively. These resistances RR6 and R6 are of comparatively lowvalue and are em- I ployed in order to adjust the resistance of the twoshunt circuits so that the same degree of field weakening is obtainedfor both motors and thereby to compensate where necessary fordifferences I in the cable and contact resistances of the parts of theequipment These additional where not required.

Under control of the limit switch contacts I10 movement of the drum mayproceed to the thirtyeighth position which corresponds with the positiond of the master controller. At this position of the drum the segments ofthe interlock contacts I26 disengage the finger I80 and the circuit forthe feed coil I10 is broken at said interlock contacts. If, however, theaccelerating drutn'ISI is actuated to the fourth position the saidcircuit is maintained through conductor I I I, contacts oi relay Ito,which will be closed and contact finger I80, so that under control ofthe limit switch the associated with the two motors. resistances may beomitted movement of the drum switch may proceed to the forty-fifth andfinal position-providing the manimum obtainable amount of fieldweakening.

The movement of the drum switch may be terminated at any desired pointby return of the accelerating drum Iii of the master controller to theprevious operative position, whereby the interlock contacts I26 willdisconnect the circuit of the feed coil I63.

Upon return oithe accelerating drum Hi to the oif position the forwardor reverse wire I30 or I39, and the conductor I00 are die-energized. Thecoils OCLSI, OCLS, 0CLS3 and 00152 of the four line switches'are therebytie-energized and said switches open to ment from the supply conductors.The de-energization of conductor I40 results in the de-energization ofconductor I40b the interlock contacts I25 tie-energized, whilst the offcoil I 68 and the re.- lease coil I69 are also de-energized due to thede-energization of conductor I400. The de-energization of coil I68 ventsthe servo motor operatthe-feed coil "I10 is ing plunger to atmospherewhilst the de-energizavalve pertion ofthe coil I 69 opens the releasemitting free-flow of the liquid of the servo motor. The de-energizationof coil I10 applies air pressure to the'return piston of the servo motordevice whereby the drum switch is returned to the disconnect theequipand thereby through "011 position. It will be seen'that,re-application of power to the motors is prevented until the drumposition has been returned completely to the "oiT position since theinterlockcontacts I69 in circuit with the operating coils of the line.switches LSI and LS4 are opened upon opening of the line switch LS1 asabove described and the same circuits may only be re-energized uponclosure of the interlock contacts I which are closed in the oiP positionof the drum. Furthermore, energization of the coil I10 from'theconductor Idflb cannot be again effected until the closure of theinterlock contacts I64 resulting from closure of the line switch LS4.Due, however, to the arrangement of the interlock contacts I26 inassociation with the finger I12 the coil I1 is established andacceleration of the equipment may proceed as hereinbefore described.Just before the drum switch reaches the "011 position a restriction isintroduced into the release valve by themovement of the piston so as tocushion movement of the drum at the end of the return movement.

-In the event of an overload on the motors the contacts I6I of theoverload relays are opened whereby to tie-energize the coils OCLSI,OCLSI, OCLSO and OCLSZ. The four line switches are thus opened todisconnect the motor equipment from the supply conductors as abovedescribed. The opening of the LS4 line switch de-energizes the conductorlock contacts IBQ and air pressure is removed from the operating pistonof the servo motor by de-energization of the coil I13. The drum switchis thus stopped with no pressure on either pistonbut with the feed valvestill open due to the energization of feed coil I10. In order to resetthe overload trip the push button I36 must beepercoil Id'I. The circuitof conductor i106 includes however the interlock contacts I 01 on theaccel crating drum IM and the interlock contacts its oi the drum switch,which interlock contacts are closed only when the master'controller andthe drum switch occupy their respective "ofl" positions. In order toe'fiect this reset operation it is thus necessary for the returned tothe o switch to follow to its oil? position.

In the case of an'interruption of the supply to the equipment thecontacts I58 and I1? oi the no-load no-current relays are opened,whereby to de-energize the coilsOCLSI, OCLS, OCLS3 and OCLSE and the.four vline switches are again opened as in the case of an overload,whilst the movement of the drum switch-is similarly stopped.

Upon reinstatement of the supply voltage the line switches cannot bereclosed until the master con-- troller and drum switch are returned totheir on positions as in the case of an overload.

I00 and I06 oi the one orseveral equipments operating together inmultiple unit are all connected position thereby Ililb due to theopening or intermaster controller to be position and for the drum Duringaccelerating operation the interlock. and Ill 1 and I63 are connectedtogether. The conductors across the supply conductors in series with oneanother and with a suitable signal device located I9I and I92 areconnected together at the interlock contacts I26.

In order to test the operation of the equipmentthe trip push button I34may be actuated to energize conductor I45 and the coil I61 ofthe tripelement. The line switches are thus tripped open and the mastercontroller may be actuated to its fifth position whereby movement of thedrum switch to its final position will take place rapidly since thelimit switch contacts I19 remain closed due to the fact that no powercurrent fiows since the line switches are open. The interlock contactsI64 of the now open line switch LS4 are under these conditionsshortcircuited by the contacts I66 operated by the trip element coilI61, whereby the energization of conductor 0b and coil IIll ismaintained. When all the equipments of the train reach the finalposition the contact fingers I9I and I92 are connected together in theseveral equipments to complete the circuit 01 the said signalling means.Should such signal not be obtained the test plugs I of each of theseveral equipments may be short-circuited in turn when the signal willbe obtained upon short-circuit oi the test plug associated with thefaulty equipment or equipments, that is to say each equipment in whichthe drum switch'has not been actuated to the final position.

It will be appreciated that the several arrangements according to theinvention possess the advantage of simplicity and employ only apparatusof well established kind.

It is to be understood that various modifications may be made in thearrangements above described without departing from the-scope of theinvention. 7 r

I claim:

1. In an electric motor controller, a plurality of resistance sections,switching means m controlling the connection of said resistance sectionsin circuit with a motor, and means for sequentially controlling saidswitching means to connect said resistance sections initially in seriesand for thereafter progressively excluding said resistance sections fromthe circuit oisthe motor with the exception of one section, connectingsaid excluded sections in series with each other and in parallel withsaid remaining section, and then excluding said series connectedsections with the exception of one section, this operation beingrepeated until said sections are connected in parallel with one anotherin the circuit of the motor.

2. In an electric motor controller, a plurality of resistance sections,a contact drum for controlling the connection of said resistancesections in circuit with a motor, contact members on said drum forinitially connecting said resistancesections in series and forthereafter progressively excluding said resistance sections .irom thecircult of the motor with the exception of one sec-,-

tion, connecting said excluded sections in series with each other and inparallel with said remaining section, and thenexcludlng said seriesconnected sections with the exception of one section, this operationbeing repeated until the circuit of said motor with the exception of onesection, connecting said excluded sections in series-with each other andin parallel with said remaining section, then excluding said seriesconnected sections with the exception of one section, this operationbeing repeated until said sections are connected in parallel with oneanother in the circuit of said motor, and contact members on said drumfor thereafter excluding all of said resistance sections and forconnecting certain of said resistance sections in series with each otherin parallel with said field winding for further field weakening.

4. An electric motor control system comprising in combination with amotor, a resistance comprising a plurality of series connected sections,a bus conductor, a series of tapping connections from said resistance tosaid bus conductor, a

switch in each of said tapping connections,

switches in said, bus conductor between the points of connectiontherewith of said tapping connections, a second bus conductor, a secondset of resistance tappings intercalated with said first set connected tosaid second bus conductor, a switch in each of said tapping connections,and control means for said switches for connecting one of said busconductors to a source of electrical supply and the other of said busconductors to said motor to thereby connect said resistance in serieswith said motor, and to thereafter effect a succession of steps ofalternate tap-stepping and interconnection of tappings to connectgradually said resistance sections in parallel with each other.

5. An electric motor control system comprising V in combination with amotor, a resistance comprising a plurality of series connected sections,a bus wire, a series of tapping connections from said resistance to saidbus wire, a switch in each of said tapping connections, switches in saidbus wire between the points of connection therewith of said tappingconnections, a second bus wire, a second set of resistance tappingsintercalated with said first set connected to said second bus wire, aswitch in each of said tapping connections, and control means for saidswitches for connecting one of said bus wires to a source of electricalsupply and the other of said bus wires to said motor to thereby connectsaid resistance in series with said motor, and to thereafter efiect asuccession of steps of alternate tapstepping and interconnection oftappings to gradually connect said resistance sections in parallel witheach.

connections, switches in said bus I wire between the points ofconnection of said tapping connections; a second bus wire, a second setof tappings intercalate'd with said first set connected to said secondbus-wire, a switch in each of said tapping connections, connectionsbetween the ends of said resistance and said first bus wire, switchesfor selectively connecting one end of said resistance to each side ofsaid field winding, a switch connecting said second bus wire to one sideof said field winding, a switch connecting the other end of saidresistance to said second bus wire, means for controlling said switchesto connect said resistance in series with the armature of said motor andthen to gradually connect the sections of said resistance between saidtappings in parallel with each other in circuit with said motor, saidresistance sections being first excluded with the exception of one, thenreconnected in series with each other in parallel with said one, thenexcluded with the exception of one section, this operation beingrepeated until said sections are connected in parallel, and means forcontrolling said switches to exclude said resistance from the armaturecircuit of said motor, then connect said resistance in parallel withsaid series field winding and thereafter progressively exclude at leasta portion of said resistance.

'7. An electric motor control system comprising in combination with amotor provided with "a series field winding, a resistance comprising aplurality of series connected sections, a drum controller forcontrolling the connection of said resistance in the circuit of saidmotor, said controller being provided with two groups of adjacentcontact fingers, connections between said groups respectively and twointercalated sets of said tappings on saidresistance between saidsections, the connections between each set of tappings and itsassociated fingers crossing the connections between the other set' 01'tappings and its associated fingers, and contact members on saiddrum'i'orjconnecting said resistance in series with said motor andforthereafter efiecting a succession of steps 01' alternate tap-steppingand interconnection of tappings to connect gradually the sections ofsaid resistance in parallel with each other in the circuit of saidmotor.

-' a 8; An electric motor control system comprising in combination witha motor provided with a series field winding, a resistance comprising aplurality of series connected sections, a drum controller forcontrolling the connection of said resistance in the circuit 01' saidmotor, said controller being provided with two groups of adiacentcontact fingers, connections between said groups respectively and twointercalatedsets of said tappings on said resistance between saidsections, the connections between each set of tappings and itsassociated fingers crossing the connections between the other set oftappings and its associated fingers-and contact members on said drumfcr'initially connecting said resistance in series with said motorandfor thereafter progressively excluding the sections of said resistancebetween said tappings from the circuit of said motorwith the exceptionof one section, connecting said excluding sections in series with eachother and, parallel with the remaining section, and then excludingsaid'series connected sections with theexception of one, section, etc.,

until said sections are connected in parallel with one another in thecircuit of said motor.

9. The combinationin a series parallel control system for two electricmotors provided with series field windings, two sets of resistancesections, one for each motor, rotary switching means for progressivelycontrolling the energization of said motors and the connections of saidresistance'sections so as to initially connect said motors in serieswitheach other, and said sets of resistances in serieswith each other incircuit with said motors, the resistance sections of each set beingconnected in series with each other, for thereafter excluding saidsections from said sets with the exception of one section in each set,then connecting the excluded'sections of each set in series with eachother in parallel with the re-- ,maining section and excluding saidseries connected sections from said sets with the exception of one, thisoperation being repeated until said sections of each set are connectedin parallel with each other, and rotary switching means for thenconnecting said motors in parallel with each other with certain of theresistance sections in each set included in the circuit with each motorin series with each other; for progressively connecting the resistancesections in each set in parallel with each other by the series parallelmethod previously described, and for thereafter excluding saidresistances completely from the circuit of each motor and thenconnecting the resistance sections in said sets in series with eachother and in parallelrespectively with said field windings.

1,0. The combination in a series parallel control system fortwo electricmotors provided with series field windings, twosets of resistancesections, one for .each motor, a contact drum for progressivelycontrolling the energization of said motors and the connections of saidresistance sections, contact members on said drum for initiallyconnecting said motors in series with each other 7 and said sets ofresistances. in series with each other in circuit with said motors, theresistance sections of each set being connected in'series with eachother, contact members on said drum for thereafter excluding 1 saidsections alternately from said sets with the exception of one section ineach set, then connecting the excluded sections of each set in serieswith each other in parallel with the-remaining section and excludingsaid series connected sections alternately from saidsets with theexception of one, this operation being repeated until said sections ofeach setare connected in parallel with each other, contact members onsaid drum for then connecting said motors in parallel .with each otherwith certain of the resistance sections in each set in series with eachother included in the circuit with each motor, contact members on saiddrum for thereafter progressively connecting the resistance sections ineach set in parallel with each other by the series parallel methodpreviously described; contact members on said drum forthereafterexcluding said resistances completely from the oil"- cuit ofea'ch motorand then connecting the resistance sections in said sets in series witheach other and in parallel respectively with said field windings.

TRAIN GRAY;

